4.5 Analysis of Rainy Days Data and Its Rain Attenuation
4.5.2 Time Series of the Experimental Data for Rainy days
This sub-section gives examples of the time series for various rainy days showing low, moderate and high rainy days. The received signal levels (dBm) for these rainy days are also shown. The total attenuation (dB) is extracted from the received signal by discounting the free space loss of - 41 dBm from the received signal. The total attenuation incorporates the clear air effects and the effect of the rain rate recorded along the terrestrial link. The rain attenuation (dB) along the terrestrial path in each of the observed day is determined by deducting average clear air attenuation in the month (see Fig. 4-7b) from the total attenuation (dB).
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Fig. 4-8 shows a high rainy day time series with a maximum rain rate of 79 mm/h in this particular day (September 25, 2004). The total received signal shown in Fig. 4-9 incorporates the free space loss, rain losses, and other clear air effects. Therefore, subtracting the free space loss of -41 dBm and the clear-air attenuation of 2.46 dB calculated from the non-rain faded average for the month September (as shown in Fig. 4-7b) from the total received signal for this chosen day in September, the rain attenuation along the terrestrial path is determined. The rain attenuation time series is shown in Fig. 4-10. For this day (September 21), the highest rain rate of 79 mm/h has a rain attenuation of about 25.42 dB as shown in Fig. 4-10.
Fig. 4-11 below shows another example of a high rainy day which occurred on 21st of October with the highest rain rate of 73 mm/h occurring at around 8:00 pm. The rain occurred between 7:45 pm – 11: 00 pm as shown in Fig. 4-11. The average non-rain faded signal level estimated for this month was -43.46 dBm, i.e. an average clear-air attenuation of 2.46 dB is expected along the path for the month of October. Subtracting the free space loss of -41 dBm and the average clear- air attenuation from the actual received signal level (as shown in Fig. 4-12), the rain attenuation for this particular day in October can be estimated. Fig. 4-13 shows the time series for the rain attenuation for high rainy day in October. This day has a high rain rate of 73 mm/h with corresponding rain attenuation of 21.57 dB.
Fig. 4-14 shows an example of a moderate rainy day in Durban which occurred on 29th February, 2004. The rain started around 4:40 pm and ends around 10: 00 pm getting to its climax around 5:00pm with a rain rate of 37 mm/h. The time series for the rainy day is shown in Fig. 4-14 below. Following this figure is the time series for the total received signal level for this day (Fig.
4-15). Fig. 4-16 shows the rain attenuation for the moderate rainy day, after which the free space loss of -41 dBm and the average clear air attenuation of about 0.68 dB for the February has been deducted from the actual received signal level.
Fig. 4-17 above shows the time series for a low rainy day. This occurred on the 27th of November, 2004. The rain rate ranges between 1 – 6 mm/ h and getting to its peak around 5: 48 pm with a rain rate of 6 mm/h. Fig 4-18 also shows the total received signal for this particular rainy day with the lowest value of -51.85 dBm which is induced by the 6 mm/h. The rain attenuation was extracted from the time series of the received signal level by subtracting the free space loss of -41 dBm and the average clear-air attenuation of -1.41dB determined from the non-rain faded average for the month of November. The highest attenuation for this low rainy day is 8.46 dB.
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0 20 40 60 80
12:00am 1:00am 2:00am 3:00am 4:00am 5:00am 6:00am 7:00am 8:00am 9:00am 10:00am 11:00am 12:00pm 1:00pm 2:00pm 3:00pm 4:00pm 5:00pm 6:00pm 7:00pm 8:00pm 9:00pm 10:00pm 11:00pm
Time
Rain rate (mm/h)
Fig. 4- 8: Time series for a high rainy day, September 25, 2004
-51.22 -53.41
-61.01
-68.88 -70
-65 -60 -55 -50 -45 -40
12:00am 1:00am 2:00am 3:00am 4:00am 5:00am 6:00am 7:00am 8:00am 9:00am 10:00am 11:00am 12:00pm 1:00pm 2:00pm 3:00pm 4:00pm 5:00pm 6:00pm 7:00pm 8:00pm 9:00pm 10:00pm 11:00pm
Time
Received signal level (dBm)
Fig. 4- 9: The received signal time series for a high rainy day, September 25, 2004
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17.55
7.28 9.95
25.42
0 5 10 15 20 25 30
12:00am 1:00am 2:00am 3:00am 4:00am 5:00am 6:00am 7:00am 8:00am 9:00am 10:00am 11:00am 12:00pm 1:00pm 2:00pm 3:00pm 4:00pm 5:00pm 6:00pm 7:00pm 8:00pm 9:00pm 10:00pm 11:00pm
Time
Rain attenuation (dB)
Fig. 4- 10: The rain attenuation time series for a high rainy day, September 25, 2004
0 10 20 30 40 50 60 70 80
12:00am 1:00am 2:00am 3:00am 4:00am 5:00am 6:00am 7:00am 8:00am 9:00am 10:00am 11:00am 12:00pm 1:00pm 2:00pm 3:00pm 4:00pm 5:00pm 6:00pm 7:00pm 8:00pm 9:00pm 10:00pm 11:00pm
Time
Rain rate (mm/h)
Fig. 4- 11: Time series for a high rainy day, October 21, 2004
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-47.76
-60.48 -59.24
-65.45
-70 -65 -60 -55 -50 -45 -40
12:00am 1:00am 2:00am 3:00am 4:00am 5:00am 6:00am 7:00am 8:00am 9:00am 10:00am 11:00am 12:00pm 1:00pm 2:00pm 3:00pm 4:00pm 5:00pm 6:00pm 7:00pm 8:00pm 9:00pm 10:00pm 11:00pm
Time
Received signal level (dBm)
Fig. 4- 12: The received signal time series for a high rainy day, October 21, 2004
4.3 21.57
16.21 17.02
3.22
0 5 10 15 20 25
12:00am 1:00am 2:00am 3:00am 4:00am 5:00am 6:00am 7:00am 8:00am 9:00am 10:00am 11:00am 12:00pm 1:00pm 2:00pm 3:00pm 4:00pm 5:00pm 6:00pm 7:00pm 8:00pm 9:00pm 10:00pm 11:00pm
Time
Rain attenuation (dB)
Fig. 4- 13: The rain attenuation time series for a high rainy day, October 21, 2004
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0 10 20 30 40
12:00am 1:00am 2:00am 3:00am 4:00am 5:00am 6:00am 7:00am 8:00am 9:00am 10:00am 11:00am 12:00pm 1:00pm 2:00pm 3:00pm 4:00pm 5:00pm 6:00pm 7:00pm 8:00pm 9:00pm 10:00pm 11:00pm
Time
Rain rate (mm/h)
Fig. 4- 14: Time series for a moderate rainy day, February 29, 2004
-48.12 -49.61
-56.61 -57.99 -60
-55 -50 -45 -40 -35
12:00am 1:00am 2:00am 3:00am 4:00am 5:00am 6:00am 7:00am 8:00am 9:00am 10:00am 11:00am 12:00pm 1:00pm 2:00pm 3:00pm 4:00pm 5:00pm 6:00pm 7:00pm 8:00pm 9:00pm 10:00pm 11:00pm
Time
Received signal level (dBm)
Fig. 4- 15: The received signal time series for a moderate rainy day, February 29, 2004
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6.35 7.63
14.93 16.97
0 4 8 12 16
12:00am 1:00am 2:00am 3:00am 4:00am 5:00am 6:00am 7:00am 8:00am 9:00am 10:00am 11:00am 12:00pm 1:00pm 2:00pm 3:00pm 4:00pm 5:00pm 6:00pm 7:00pm 8:00pm 9:00pm 10:00pm 11:00pm
Time
Rain Attenuation (dB)
Fig. 4- 16: The rain attenuation time series for a moderate rainy day, February 29, 2004
0 1 2 3 4 5 6 7
12:00am 1:00am 2:00am 3:00am 4:00am 5:00am 6:00am 7:00am 8:00am 9:00am 10:00am 11:00am 12:00pm 1:00pm 2:00pm 3:00pm 4:00pm 5:00pm 6:00pm 7:00pm 8:00pm 9:00pm 10:00pm 11:00pm
Time
Rain rate (mm/h)
Fig. 4- 17: Time series for a low rainy day, November 27, 2004
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-45.76
-51.85
-55 -50 -45 -40 -35
12:00am 1:00am 2:00am 3:00am 4:00am 5:00am 6:00am 7:00am 8:00am 9:00am 10:00am 11:00am 12:00pm 1:00pm 2:00pm 3:00pm 4:00pm 5:00pm 6:00pm 7:00pm 8:00pm 9:00pm 10:00pm 11:00pm
Time
Received signal level (dBm)
Fig. 4- 18: The received signal time series for a low rainy day, November 27, 2004
1.95
2.65 8.46
0 2 4 6 8 10
12:00am 1:00am 2:00am 3:00am 4:00am 5:00am 6:00am 7:00am 8:00am 9:00am 10:00am 11:00am 12:00pm 1:00pm 2:00pm 3:00pm 4:00pm 5:00pm 6:00pm 7:00pm 8:00pm 9:00pm 10:00pm 11:00pm
Time
Rain attenuation (dB)
Fig. 4- 19: The rain attenuation time series for a low rainy day, November 27, 2004
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